A point 
on a regular surface 
is said to be hyperbolic if the Gaussian
curvature 
or equivalently, the principal curvatures 
and 
, have opposite signs.
Hyperbolic Point
See also
Anticlastic, Elliptic Point, Gaussian Curvature, Hyperbolic Fixed Point, Parabolic Point, Planar Point, SynclasticExplore with Wolfram|Alpha
References
Gray, A. Modern Differential Geometry of Curves and Surfaces with Mathematica, 2nd ed. Boca Raton, FL: CRC Press, p. 375, 1997.Referenced on Wolfram|Alpha
Hyperbolic PointCite this as:
Weisstein, Eric W. "Hyperbolic Point." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/HyperbolicPoint.html